How to programmatically tell if a Bluetooth device is connected

Question

I understand how to get a list of paired devices but how can I tell if they are connected    It must be possible since I see them listed in my phone s Bluetooth device list and it states their connection status

User · Answer

This code is for the headset profiles  probably it will work for other profiles too  First you need to provide profile listener  Kotlin code    private val mProfileListener   object   BluetoothProfile ServiceListener       override fun onServiceConnected profile  Int  proxy  BluetoothProfile            if  profile    BluetoothProfile HEADSET               mBluetoothHeadset   proxy as BluetoothHeadset                        override fun onServiceDisconnected profile  Int            if  profile    BluetoothProfile HEADSET                mBluetoothHeadset   null                     Then while checking bluetooth   mBluetoothAdapter getProfileProxy context  mProfileListener  BluetoothProfile HEADSET  if   mBluetoothAdapter isEnabled        return Intent BluetoothAdapter ACTION REQUEST ENABLE      It takes a bit of time until onSeviceConnected is called  After that you may get the list of the connected headset devices from   mBluetoothHeadset   connectedDevices

User · Answer

Add bluetooth permission to your AndroidManifest    lt uses-permission android name  android permission BLUETOOTH    gt    Then use intent filters to listen to the ACTION ACL CONNECTED  ACTION ACL DISCONNECT REQUESTED  and ACTION ACL DISCONNECTED broadcasts   public void onCreate                 IntentFilter filter   new IntentFilter        filter addAction BluetoothDevice ACTION ACL CONNECTED       filter addAction BluetoothDevice ACTION ACL DISCONNECT REQUESTED       filter addAction BluetoothDevice ACTION ACL DISCONNECTED       this registerReceiver mReceiver  filter        The BroadcastReceiver that listens for bluetooth broadcasts private final BroadcastReceiver mReceiver   new BroadcastReceiver          Override     public void onReceive Context context  Intent intent            String action   intent getAction            BluetoothDevice device   intent getParcelableExtra BluetoothDevice EXTRA DEVICE            if  BluetoothDevice ACTION FOUND equals action                      Device found                   else if  BluetoothDevice ACTION ACL CONNECTED equals action                      Device is now connected                   else if  BluetoothAdapter ACTION DISCOVERY FINISHED equals action                      Done searching                   else if  BluetoothDevice ACTION ACL DISCONNECT REQUESTED equals action                      Device is about to disconnect                   else if  BluetoothDevice ACTION ACL DISCONNECTED equals action                      Device has disconnected                                   A few notes    There is no way to retrieve a list of connected devices at application startup  The Bluetooth API does not allow you to QUERY  instead it allows you to listen to CHANGES   A hoaky work around to the above problem would be to retrieve the list of all known paired devices    then trying to connect to each one  to determine if you re connected    Alternatively  you could have a background service watch the Bluetooth API and write the device states to disk for your application to use at a later date

User · Answer

Big thanks to Skylarsutton for his answer  I m posting this as a response to his  but because I m posting code I can t reply as a comment  I already upvoted his answer so am not looking for any points  Just paying it forward   For some reason BluetoothAdapter ACTION ACL CONNECTED could not be resolved by Android Studio  Perhaps it was deprecated in Android 4 2 2  Here is a modification of his code  The registration code is the same  the receiver code differs slightly   I use this in a service which updates a Bluetooth-connected flag that other parts of the app reference       public void onCreate                           IntentFilter filter   new IntentFilter            filter addAction BluetoothDevice ACTION ACL CONNECTED           filter addAction BluetoothDevice ACTION ACL DISCONNECT REQUESTED           filter addAction BluetoothDevice ACTION ACL DISCONNECTED           this registerReceiver BTReceiver  filter                The BroadcastReceiver that listens for bluetooth broadcasts     private final BroadcastReceiver BTReceiver   new BroadcastReceiver          Override     public void onReceive Context context  Intent intent            String action   intent getAction             if  BluetoothDevice ACTION ACL CONNECTED equals action                   Do something if connected             Toast makeText getApplicationContext     BT Connected   Toast LENGTH SHORT  show                      else if  BluetoothDevice ACTION ACL DISCONNECTED equals action                   Do something if disconnected             Toast makeText getApplicationContext     BT Disconnected   Toast LENGTH SHORT  show                        else if

User · Answer

BluetoothAdapter getDefaultAdapter   isEnabled -  returns true when bluetooth is open  val audioManager   this getSystemService Context AUDIO SERVICE  as  AudioManager  audioManager isBluetoothScoOn -   returns true when device connected

User · Answer

There is an isConnected function in BluetoothDevice system API in https   android googlesource com platform frameworks base   master core java android bluetooth BluetoothDevice java  If you want to know if the a bounded paired  device is currently connected or not  the following function works fine for me    public static boolean isConnected BluetoothDevice device        try           Method m   device getClass   getMethod  isConnected    Class    null           boolean connected    boolean  m invoke device   Object    null           return connected        catch  Exception e            throw new IllegalStateException e

User · Answer

I was really looking for a way to fetch the connection status of a device  not listen to connection events   Here s what worked for me   BluetoothManager bm    BluetoothManager  context getSystemService Context BLUETOOTH SERVICE   List lt BluetoothDevice gt  devices   bm getConnectedDevices BluetoothGatt GATT   int status   -1   for  BluetoothDevice device   devices      status   bm getConnectionState device  BLuetoothGatt GATT        compare status to         BluetoothProfile STATE CONNECTED        BluetoothProfile STATE CONNECTING        BluetoothProfile STATE DISCONNECTED        BluetoothProfile STATE DISCONNECTING

User · Answer

In my use case I only wanted to see if a Bluetooth headset is connected for a VoIP app  The following solution worked for me   public static boolean isBluetoothHeadsetConnected         BluetoothAdapter mBluetoothAdapter   BluetoothAdapter getDefaultAdapter        return mBluetoothAdapter    null  amp  amp  mBluetoothAdapter isEnabled                amp  amp  mBluetoothAdapter getProfileConnectionState BluetoothHeadset HEADSET     BluetoothHeadset STATE CONNECTED       Of course you ll need the Bluetooth permission     lt uses-permission android name  android permission BLUETOOTH    gt

[android] How to programmatically tell if a Bluetooth device is connected?

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